System and method for inventory management using mobile drive units

1. A method for inventory management, comprising:

deploying a first mobile drive unit having first dimensions in a workspace;

deploying a second mobile drive unit having second dimensions in the workspace, wherein the first and second dimensions are different;

deploying a management module configured to maintain a three-dimensional reservation space in which the first mobile drive unit is operable to reserve a first three-dimensional reservation volume corresponding to the first dimensions and the second mobile drive unit is operable to reserve a second three-dimensional reservation volume corresponding to the second dimensions; and

wherein the first and second mobile drive units are operable to transport inventory items to a plurality of inventory stations in the same workspace.

2. The method of claim 1 , further comprising

determining a first path for the first mobile drive unit;

determining a second path for the second mobile drive unit; and

reserving a first segment of the first path, the first segment comprising a first space associated with the first dimensions of the first mobile drive unit.

3. The method of claim 2 , wherein the first space comprises one of a volume, a cell, and a footprint.

4. The method of claim 2 , further comprising:

receiving a request to reserve a second segment of a second path;

determining whether the requested second segment intersects with a reserved space; and

determining that the requested second segment does not intersect, with the reserved space.

5. The method of claim 2 , wherein reserving a first segment further comprises:

determining that the first mobile drive unit is coupled to an inventory holder;

modifying the first space based on the dimensions of the inventory holder; and

reserving a modified first segment comprising the modified first space.

6. The method of claim 2 , further comprising:

applying a reservation policy, wherein reserving the first segment is based on determining that the reservation does not conflict with the reservation policy.

7. The method of claim 6 , wherein the reservation policy is based on at least one of an inventory holder location, a predetermined number of maximum drives, a predetermined maximum weight, a predetermined maximum speed, and an inventory type.

8. The method of claim 2 , wherein reserving a first segment further comprises:

receiving a request to reserve the first segment of the first path, the first segment representing a physical location of an inventory holder;

determining that the first segment does not intersect with the inventory holder; and

after reserving the first segment, moving the first mobile drive unit under the inventory holder.

9. The method of claim 2 , wherein reserving a first segment further comprises:

receiving a request to reserve the first segment of the first path;

determining that the requested first segment comprises a partially unreserved portion; and

reserving the partially unreserved portion.

10. The method of claim 1 , further comprising:

determining a capability of one of the plurality of inventory stations; and

assigning an order associated with the first and second mobile drive units to the inventory station based on the capability.

11. The method of claim 2 , wherein reserving a first segment further comprises:

receiving a request to reserve the first segment of the first path;

determining that the requested first segment comprises a partially reserved portion and a partially unreserved portion;

partially granting the request of the partially unreserved portion;

further determining that an additional portion of the partially reserved portion has become unreserved; and

partially granting the request of the additional portion.

12. The method of claim 11 , further comprising:

determining that the additional portion conflicts with a reservation policy; and

reducing the additional portion based on the reservation policy.

13. The method of claim 1 , wherein the first and second mobile drive units are each operable to transport inventory items to one of the plurality of inventory stations in the same workspace.

14. A system for inventory management comprising:

a first mobile drive unit having first dimensions;

a second mobile drive unit having second dimensions, wherein the first and second dimensions are different;

a management module configured to maintain a three-dimensional reservation space in which the first mobile drive unit is operable to reserve a first three-dimensional reservation volume corresponding to the first dimensions and the second mobile drive unit is operable to reserve a second three-dimensional reservation volume corresponding to the second dimensions; and

a plurality of inventory holders, the first and second mobile drive units each operable to transport at least one of the inventory holders.

15. The system of claim 14 , further comprising a management module operable to:

determine a first path for the first mobile drive unit;

determine a second path for the second mobile drive unit; and

reserve a first segment of the first path, the first segment comprising a first space associated with the first dimensions of the first mobile drive unit.

16. The system of claim 15 , wherein the first space comprises one of a volume, a cell, and a footprint.

17. The system of claim 15 , the management module further operable to:

receive a request to reserve a second segment of a second path;

determine whether the requested second segment intersects with a reserved space; and

determine that the requested second segment does not intersect with the reserved space.

18. The system of claim 15 , the management module further operable to:

determine that the first mobile drive unit is coupled to an inventory holder;

modify the first space based on the dimensions of the inventory holder; and

reserve a modified first segment comprising the modified first space.

19. The system of claim 15 , the management module further operable to:

apply a reservation policy, wherein reserving the first segment is based on determining that the reservation does not conflict with the reservation policy.

20. The system of claim 19 , Wherein the reservation policy is based on at least one of an inventory holder location, a predetermined number of maximum drives, a predetermined maximum weight, a predetermined maximum speed, and an inventory type.

21. The system of claim 15 , the management module further operable to:

receive a request to reserve the first segment of the first path, the first segment representing a physical location of an inventory holder;

determine that the first segment does not intersect with the inventory holder; and

wherein after reserving the first segment, the first mobile drive unit moves under the inventory holder.

22. The system of claim 15 , the management module further operable to:

receive a request to reserve the first segment of the first path;

determine that the requested first segment comprises a partially unreserved portion; and

reserve the partially unreserved portion.

23. The system of claim 14 , further comprising a management module operable to:

determine a capability of one of a plurality of inventory stations; and

assign an order associated with the first and second mobile drive units to the inventory station based on the capability.

24. The system of claim 15 , the management module further operable to:

receive a request to reserve the first segment of the first path;

determine that the requested first segment comprises a partially reserved portion and a partially unreserved portion;

partially grant the request of the partially unreserved portion;

further determine that an additional portion of the partially reserved portion has become unreserved; and

partially grant the request of the additional portion.

25. The system of claim 24 , the management module further operable to:

determine that the additional portion conflicts with as reservation policy; and

reduce the additional portion based on the reservation policy.

26. The system of claim 14 , further comprising a plurality of inventory stations, wherein the first and second mobile drive units are each operable to transport a least one of the plurality of inventory holders to a least one of the plurality of inventory stations.

27. The system of claim 26 , wherein the plurality of inventory stations comprise:

a plurality of first inventory stations operable to interact with inventory items from the first mobile drive units;

a plurality of second inventory stations operable to interact with inventory items from the second mobile drive units; and

a plurality of third inventory stations operable to interact with inventory items from the first and second mobile drive units.

28. The system of claim 14 , wherein the plurality of inventory holders comprise:

a plurality of first inventory holders having third dimensions;

a plurality of second inventory holders having fourth dimensions, wherein the third and fourth dimensions are different;

the first mobile drive unit is further operable to transport the plurality of first inventory holders; and

the second mobile drive unit is further operable to transport the plurality of second inventory holders.

29. The system of claim 28 , wherein the first mobile drive unit is further operable to transport the second inventory holders.

30. The system of claim 28 , wherein the second mobile drive unit is further operable to transport the first inventory holders.

31. A management module comprising logic encoded in a non-transitory medium and when executed by a processor operable to:

facilitate management of a first mobile drive unit having first dimensions in an inventory management system;

facilitate management of a second mobile drive unit having second dimensions in the inventory management system, wherein the first and second dimensions are different; and

maintain a three-dimensional reservation space in which the first mobile drive unit is operable to reserve a first three-dimensional reservation volume corresponding to the first dimensions and the second mobile drive unit is operable to reserve a second three-dimensional reservation volume corresponding to the second dimensions; and

wherein the first and second mobile drive units are operable to transport inventory items to a plurality of inventory stations in the inventory management system.

32. The management module of claim 31 , further operable to:

determine a first path for the first mobile drive unit;

determine a second path for the second mobile drive unit; and

reserve a first segment of the first path, the first segment comprising a first space associated with the first dimensions of the first mobile drive unit.

33. The management module of claim 32 , wherein the first space comprises one of a volume, a cell, and a footprint.

34. The management module of claim 32 , further operable to:

receive a request to reserve a second segment of a second path;

determine whether the requested second segment intersects with a reserved space; and

determine that the requested second segment does not intersect with the reserved space.

35. The management module of claim 32 , further operable to:

determine that the first mobile drive unit is coupled to an inventory holder;

modify the first space based on the dimensions of the inventory holder; and

reserve a modified first segment comprising the modified first space.

36. The management module of claim 32 , further operable to:

apply a reservation policy, wherein reserving the first segment is based on determining that the reservation does not conflict with the reservation policy.

37. The management module of claim 36 , wherein the reservation policy is based on at least one of an inventory holder location, a predetermined number of maximum drives, a predetermined maximum weight, a predetermined maximum speed, and an inventory type.

38. The management module of claim 32 , further operable to:

receive a request to reserve the first segment of the first path, the first segment representing a physical location of an inventory holder;

determine that the first segment does not intersect with the inventory holder; and

wherein after reserving the first segment, the first mobile drive unit moves under the inventory holder.

39. The management module of claim 32 , further operable to:

receive a request to reserve the first segment of the first path;

determine that the requested first segment comprises a partially reserved portion and a partially unreserved portion; and

partially grant the request of the partially unreserved portion.

40. The management module of claim 31 , further operable to:

determine a capability of one of the plurality of inventory stations; and

assign an order associated with the first and second mobile drive units to the inventory station based on the capability.

41. The management module of claim 32 , further operable to:

receive a request to reserve the first segment of the first path;

determine that the requested first segment comprises a partially reserved portion and a partially unreserved portion;

partially grant the request of the partially unreserved portion;

further determine that an additional portion of the partially reserved portion has become unreserved; and

partially grant the request of the additional portion.

42. The management module of claim 41 , further operable to:

determine that the additional portion conflicts with a reservation policy; and

reduce the additional portion based on the reservation policy.